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Re: st: drop observations - if statement
From
Nick Cox <[email protected]>
To
"[email protected]" <[email protected]>
Subject
Re: st: drop observations - if statement
Date
Thu, 6 Mar 2014 10:35:11 +0000
"." may seem to mean missing in two possible senses;
1. Users may employ that coding for missing, but that's a personal
choice. Stata pays no special attention.
2. Stata will return numeric missing to -real(".")-
. di real(".")
.
Notice that Stata displayed a period or stop, meaning numeric (often
called system) missing.
But it does that to anything that can't be translated to a number:
. di real("Stata")
.
Is "." missing? Stata will answer this question for you
. di missing(".")
0
0 means false.
Nick
[email protected]
On 6 March 2014 03:03, R Zhang <[email protected]> wrote:
> thank you Jeph!
>
> I did "count if missing(cusip)", it shows zero observation. but when
> the data is openned in browse mode, cusip field is displayed as "." ,
> is that not missing?
>
> On Wed, Mar 5, 2014 at 6:00 PM, Jeph Herrin <[email protected]> wrote:
>> Are you sure any are missing?
>>
>> Try
>>
>> count if missing(cusip)
>>
>> and see what you get.
>>
>> hth,
>> Jeph
>>
>>
>>
>>
>> On 3/5/2014 5:41 PM, R Zhang wrote:
>>>
>>> Hi all,
>>>
>>> I used the following commands to drop observations based on a string
>>> variable - CUSIP- that takes missing values, i.e. delete observations
>>> with missing CUSIP,
>>>
>>> drop if cusip==""
>>>
>>> cusip is str10
>>>
>>> (0 observations deleted)
>>>
>>> could you explain why "(0 observations deleted)"?
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